1. Field of the Invention
The present invention relates to an electrical connector, and particularly to a modular jack having a built-in device providing surge suppressing protection for conductive circuits to which the connector contacts are electrically connected.
2. Description of Related Art
Modern electrical equipment typically contains complex electrical circuitry which is susceptible to damage from electrical surges. Such damage ranges from a momentary interruption of operation to total overload and burn-up of electrical circuits. In order to protect electrical equipment from damage due to overvoltage and/or overcurrent resulted from electrical surges, devices such as surge suppressors or surge protectors have been introduced. Such a surge suppressor normally contains circuitry that responds to a rate of change of a current or voltage to prevent a rise above a predetermined value of the current or voltage and typically includes resistors, capacitors, coils, tubes and semiconductor devices.
Generally, a modular jack employed in an electronic appliance, such as a telephone, cooperates with a surge suppressor to protect the electronic appliance from electrical surge. However, conventionally, the modular jack and the surge suppressor are configured as separate parts and are individually mounted on a printed circuit board, which consumes significant space on the printed circuit board. In this case, conductive circuits are further required to connect the parts with each other, which also consumes space on the printed circuit board. Thus, a modular jack with a built-in surge suppressor is desired.
Modular jacks with built-in surge suppressing device are disclosed in U.S. Pat. Nos. 4,726,638 and 5,139,442. U.S. Pat. No. 4,726,638 discloses a surge suppressing device consisting of a dielectric substrate with a ground surface area on a lower surface thereof, a plurality of surge protectors mounted on an upper surface of the substrate and connected to the ground surface area through apertures in the substrate, and a ground plate attached to the bottom of the jack housing and contacting the ground surface area. The surge suppressors are in the form of diodes and are connected to respective jack contacts via conductive paths on the substrate. The substrate is partially received in the housing and extends beyond the rear major side of the housing to engage with the ground plate, which occupies significant space. Alternatively, the substrate is attached to the bottom of the housing, whereby the height of the modular jack is increased. Furthermore, the ground plate is individually attached to a bottom surface of the housing, which requires modification to the housing according to the specific configuration of the ground plate, thereby complicating manufacture and increasing production cost.
U.S. Pat. No. 5,139,442 discloses, in FIGS. 7-11, a modular jack having a built-in surge suppressing device consisting of a grounding terminal 53 insert molded in the jack housing 10 and a varistor 51 functioning as a surge suppressor. The varistor has electrodes 52a, 52b and 52c printed on upper and lower sides thereof for respectively soldering to the jack contacts 5 and the grounding terminal 53. Accordingly, both manufacture and assembly of the modular jack are complicated since insert-molding process and tedious soldering process are employed. Furthermore, the grounding terminal has a pair of legs 55 extending along opposite outer sides of the housing for connecting with a printed circuit board 9 on which the modular jack is mounted. Thus, electrical surge received by the contacts is suppressed to ground via the varistor, the grounding terminal, the printed circuit board, and a conductive chassis within which the printed circuit board is mounted. This requires a long, high-resistance path to ground, and thus surge suppressing efficiency is adversely affected.
Hence, a modular jack having an improved built-in surge suppressing device is required to overcome the disadvantages of the prior art.
Accordingly, one object of the present invention is to provide a modular jack having a surge suppressing device including a dielectric substrate, a plurality of surge protectors and a grounding clip, all of which are completely received in an insulative housing of the modular jack.
Another object of the present invention is to provide a modular jack having an easily assembled built-in surge suppressing device.
further object of the present invention is to provide a modular jack having a built-in surge suppressing device which establishes a short, low-resistance ground path for maximum efficiency.
Yet another object of the present invention is to provide a modular jack with little modification to the existing housing configuration to accommodate a surge suppressing device.
In order to achieve the objects set forth, a modular jack in accordance with the present invention comprises an insulative housing receiving a plurality of terminals therein, a shield enclosing the insulative housing for engaging with a grounded chassis, and a surge suppressing device completely received in the insulative housing. The surge suppressing device includes a dielectric substrate with surge suppressing circuitry and conductive signal traces provided on respective opposite major sides thereof, and a grounding clip mounted on the dielectric substrate and contacting with an inner surface of the shield. The terminals are electrically connected with the conductive signal traces, and the conductive signal traces are electrically interconnected with the surge suppressing circuitry via plated tunnels defined through the dielectric substrate.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.